Refrigerating apparatus

ABSTRACT

A liquid injection type scroll compressor is used to a refrigerating apparatus using hydrocarbon fluoride refrigerant which does not contain chlorine (HFC-125/HFC-143 a /HFC-134 a ) as an operating fluid and an amount of an injected liquid is controlled according to a discharge temperature of the compressor. Further, ester oil and/or ether oil is used as refrigerator oil and a dryer is disposed in a refrigerating cycle. With this arrangement, a refrigerating cycle operation can be stably realized in a wide range without almost changing the arrangement of a conventional refrigerating apparatus.

CROSS REFERENCE TO RELATED INVENTIONS

[0001] This application is a continuation-in-part of application Ser.No. 08/528,037, filed Sep. 14, 1997, the contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a refrigerating apparatus usedto air conditioners, refrigerators and the like, and more specifically,to a refrigerating apparatus using a mixed refrigerant which does notcontain chlorine.

[0004] 2. Description of the Prior Art

[0005] Conventionally, so-called hydrocarbon fluoride refrigerantscontaining chloride such as CFC, HCFC and such like are widely used asan operating fluid for a refrigerating cycle because they are a mostsuitable substance as a refrigerant due to their excellent thermodynamicproperty and stability.

[0006] As described in, for example, Japanese Patent PublicationLaid-Open No. 3-63461, Japanese Patent Publication Laid-Open No.59-84049, Japanese Patent Publication Laid-Open No. 5-172408 and thelike, it is well known that refrigerating apparatuses using theserefrigerants prevent the overheat of compressors and achieve a widerange of an operating pressure.

[0007] Hydrocarbon fluoride substances containing chloride are notdecomposed due to their stability and reach the stratosphere byconvection. It is found that since these substances are decomposed bystrong ultraviolet rays in the sky and separate chlorine atoms whichreact with ozone, they have an action for destroying the ozone layer. ItIs determined to entirely abolish the hydrocarbon fluoride substancescontaining chloride to protect the ozone layer which has a function tocut off ultraviolet rays harmful to human bodies in the sky. AlthoughHCFC-22 which is widely used as a refrigerant for air conditioners andrefrigerators is also an object to be abolished, since it is lesseffective to the destruction of the ozone layer than CFCs designated asspecific Freons, a longer period of grace is admitted to the substance.It is essential to develop replacement refrigerants and refrigeratingapparatuses applicable to the replacement refrigerants in the period ofgrace.

[0008] At present, HFC-32, HFC-125, HFC-134a, HFC-143a, HFC-152a andsuch like, for example, as hydrocarbon fluoride refrigerants which donot contain chloride causing the destruction of the ozone layer areexamined as new refrigerants to be replaced with conventionalrefrigerants such as HCF-C22 and such like and any one of them or acombination of a plurality of them is influential. Development iscarried out aiming at a refrigerant having a performance factor such asa refrigerating capacity, efficiency and the like and a cyclic statesuch as an operating pressure, temperature and the like equivalent ornear to those of conventional refrigerants. This is because that acaution is paid to permit the replacement refrigerants to be handled inthe same manner as conventional refrigerants so that the newrefrigerants can be employed with a minimum change of the specificationof products and manufacturing apparatuses which have been applied toconventional refrigerants.

[0009] Incidentally, a compressor, cycle auxiliary components and acycle control device must be arranged to comply with the newrefrigerants so that a performance equivalent to that of conventionalproducts is maintained and a cycle state such as a range of an operatingpressure, temperature and the like is stabilized at all times. Further,when different refrigerants are used, refrigerator oils must be alsochanged to comply with the new different refrigerants. That is, althoughchlorine has a function for assisting compatibility with oil, newrefrigerants do not contain chloride causing the destruction of theozone layer as described above. Thus, the compatibility of the newrefrigerants with conventional refrigerator oils, which are mainlycomposed of mineral oils, alkylbenzene and such like and have beenwidely used to conventional refrigerants, is greatly lowered and thusthe new refrigerants cannot be used with the conventional refrigeratoroils. To cope with this problem, there is developed new refrigerator oilwhich can secure the compatibility with the new refrigerant by themolecular polarity of ether and ester.

[0010] Incidentally, when conventional refrigerator oil and a chlorinesubstance contained in a conventional refrigerant are mixed in arefrigerating cycle to which a new refrigerant is applied, the newrefrigerant and new refrigerator oil are chemically changed by themixing of them, and, for example, a material used in the cooling cyclemay be corroded by the occurrence of acid. Thus, a problem arises inthat the reliability of products is greatly lowered.

SUMMARY OF THE INVENTION

[0011] An object of the present invention is to provide a refrigeratingapparatus which can realize a cycle state such as a performance,operating pressure, temperature and the like which are equivalent tothat of a conventional refrigerating apparatus using a new refrigerantand new refrigerator oil while securing the reliability of componentswithout damaging the performance thereof.

[0012] To achieve the above object, a first feature of the presentinvention resides in an refrigerating apparatus constituting arefrigerating cycle by sequentially connecting a compressor, acondenser, a liquid receiver, an accumulator, an expansion valve and anevaporator, wherein a mixed refrigerant containing at least R-125 andR-143a is used as a refrigerant for the refrigerating cycle, ester oiland/or ether oil is used as refrigerator oil and a liquid injection typescroll compressor is used as the compressor.

[0013] A second feature of the present invention resides in that atriple-mixed refrigerant composed of 40-48 wt %, e.g., 44 wt % of R-125,47-57 wt %, e.g., 52 wt % of R-143a and up to 10 wt %, e.g., 4 wt % ofR-134a is used as a refrigerant for a refrigerating cycle, ester oiland/or ether oil is used as refrigerator oil and further a liquidinjection type scroll compressor is used as a compressor.

[0014] An example of the liquid injection type scroll compressor isarranged such that the downstream side of the condenser is connected tothe scroll compressor through a liquid injection piping, and means forcontrolling an amount of a liquid injection into the compressor isprovided in the liquid injection piping.

[0015] It is preferable that the refrigerator oil is mainly composed ofester oil of fatty acid and having a dynamic viscosity of 2-70 cSt at40° C. and 1-9 cSt at 100° C. and at least two ester linkages in amolecule. Further, the condenser can be arranged as a heat exchangerwhose piping has a diameter smaller than the refrigerant piping of aheat exchanger constituting the evaporator in order to increase a heatexchanging efficiency in the condenser. An electronic expansion valvedisposed to the liquid injection piping is most suitable as the liquidinjection amount control means and a controller is provided to adjust anamount of an injected liquid by controlling a degree of opening of theelectronic expansion valve in response to a discharge side temperatureof the compressor.

[0016] A third feature of the present invention resides in arefrigerating apparatus, which comprises a refrigerating cycle composedby sequentially connecting a scroll compressor, a condenser, a liquidreceiver, an accumulator, an expansion valve and an evaporator, atriple-mixed refrigerant composed of 40-48 wt %, e.g., 44 wt % of R-125,47-57 wt %, e.g., 52 wt % of R-143a and up to 10 wt %, e.g., 4 wt % ofR-134a used as a refrigerant for the refrigerating cycle, refrigeratoroil composed of ester oil and/or ether oil, a liquid injection pipingconnecting the downstream side of the condenser to the scrollcompressor, means provided with the liquid injection piping forcontrolling an amount of a liquid injected into the compressor, arevolution-controllable motor for driving the scroll compressor, ablower for supplying external air to the condenser and arevolution-controllable motor for the blower, means for detecting adischarge temperature of the compressor, means for detecting a liquidtemperature of the condenser, and means for detecting a temperature ofintake air to the condenser, wherein the liquid injection amount controlmeans and the motor of the blower are controlled according to valuesdetected by the detecting means. It is preferable to provide a pressurecontroller which detects a pressure of the condenser and decreases, whenthe pressure reaches a preset high pressure value, a capacity of thecompressor by decreasing revolutions of the compressor motor, whereasincreases, when the pressure reaches a present low pressure value, acapacity of the compressor by increasing revolutions of the compressormotor. Further, it is effective that when a pressure reaches the presethigh pressure value, the pressure controller decreases a high pressureby controlling revolutions of the blower motor to its full speed,whereas when the pressure reaches the preset low pressure value, thepressure controller increases the high pressure by decreasingrevolutions of the blower motor.

[0017] A fourth feature of the present invention resides in arefrigerating apparatus, which comprises a refrigerating cycle composedby sequentially connecting a scroll compressor, a condenser, a liquidreceiver, a dryer, an expansion valve, an evaporator, a strainer and anaccumulator, a triple-mixed refrigerant composes of 40-48 wt %, e.g., 44wt % of R-125, 47-57 wt %, e.g., 52 wt % of R-143a and up to 10 wt %,e.g., 4 wt % of R-134a used as a refrigerant of the refrigerating cycle,refrigerator oil composed of ester oil and/or ether oil, a liquidinjection piping connecting the downstream side of the condenser to thescroll compressor, means provided with the liquid injection piping forcontrolling an amount of a liquid injected into the compressor, whereina desiccating agent used for the dryer is composed of synthesizedzeolite in which each of fine holes extending to molecule adsorbingcavities in a crystal structure has a diameter equal to or less than 3.3angstroms which is smaller than a molecule of the hydrocarbon fluoriderefrigerant which does not contain chloride and larger than a moleculeof water.

[0018] A fifth feature of the present invention resides in that adouble-mixed refrigerant composed of R-125 and R-143a, e.g., 50 wt % ofR-125 and 50 wt % of R-143a, is used as a refrigerant for arefrigerating cycle, ester oil and/or ether oil is used as refrigeratoroil and further a liquid injection type scroll compressor is used as acompressor.

[0019] Even the refrigerating apparatus using the above refrigerant canachieve an operating pressure, temperature and performance equivalent tothose of a refrigerating apparatus using a conventional refrigerant byemploying the liquid injection type scroll compressor.

[0020] That is, when an evaporating temperature is low, an amount of arefrigerant circulating in the refrigerating cycle is decreased and atemperature of a gas discharged from the compressor is increased. As aresult, there is caused a danger that the compress motor and the likemay be seized, and the like. In the present invention, however, thecompressor is prevented from being overheated and can be operated in awide evaporating temperature by injecting a high pressure liquidrefrigerant into the section side or intermediate compression chamber ofthe compressor through the pressure reduction unit.

[0021] A capillary system, an injection valve system, an electronicexpansion valve system or a system combining them is employed as theliquid injection system so that a flow rate of an injected liquid can bemade constant to keep a temperature of a discharged gas constant. As aresult, a cycle can be stabilized and reliability can be secured.

[0022] Further, compatibility with the new refrigerant can be secured bythe employment of the ester oil and/or ether oil as the new refrigeratoroil, whereby the reliability and performance of components can besecured.

[0023] As described above, the present invention can realize therefrigerating apparatus whose capacity can be controlled in a wide rangecovering an evaporating temperature of the evaporator of −60° C. to +5°C. using the new refrigerant which does not contain chlorine causing thedestruction of the ozone layer, without almost changing the arrangementof a conventional refrigerating apparatus.

[0024] Other features, objects and merits of the present invention willbecome apparent from the following description when taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 is a system diagram of a refrigerating apparatus showing anexample of the present invention;

[0026]FIG. 2 is a system diagram of the main portion showing anotherexample of a liquid injection arrangement in FIG. 1;

[0027]FIG. 3 is a system diagram of the main portion showing a stillanother example of the liquid injection arrangement in FIG. 1;

[0028]FIG. 4 is a system diagram of the main portion showing a furtherexample of the liquid injection arrangement in FIG. 1; and

[0029]FIG. 5 is a system diagram of the main portion showing a stillfurther example of the liquid injection arrangement in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] In this embodiment, a triple-mixed hydrocarbon fluoriderefrigerant which is composed of 40-48 wt %, e.g., 44 wt % of HFC-125,47-57 wt %, e.g., 52 wt % of HFC-143a and up to 10 wt %, e.g., 4 wt % ofHFC-134a and does not contain chlorine is used as a refrigerant for arefrigerating cycle and a liquid injection type scroll compressor isused as a compressor. Alternatively, a double-mixed hydrocarbon fluoriderefrigerant which is composed of HFC-125 and HFC-143a, e.g., 50 wt % ofHFC-125 and 50 wt % of HFC-143a, and does not contain chlorine is usedas a refrigerant for the refrigerating cycle. Further, ester oil (forexample, disclosed in Japanese Patent Publication Laid-Open No.4-183788) as a new refrigerator oil and/or ether oil is used and a meansdisclosed in, for example, Japanese Patent Publication-Laid-Open No.5-231263 is used as a means for preventing the mixing of a chlorinesubstance in order to secure the reliability of an apparatus.

[0031] A specific embodiment of the present invention will be describedbelow with reference to FIG. 1.

[0032] As shown in FIG. 1, a refrigerating apparatus of the embodimentconstitutes a refrigerating cycle by sequentially connecting a scrollcompressor 1, a condenser 2, a liquid receiver 3, a dryer 4, expansionvalves 51 and 52, evaporators 61 and 62, a strainer 18, and anaccumulator 7. Further, the condenser 2 is provided with two sets ofblower motors 81 and 82 and propeller fans 91 and 92 for supplyingexternal air as shown in FIG. 1.

[0033] A hydrocarbon fluoride refrigerant which does not containchlorine causing the destruction of the ozone layer is used as arefrigerant for the refrigerating cycle.

[0034] HFC-32, HFC-125, HFC-134a, HFC-143a, HFC-152a and the like areused as this type of a refrigerant and any one of them is independentlyused or a plurality of them are used as a mixed refrigerant. Thisembodiment uses a triple-mixed refrigerant composed of 44 wt % of R-125,52 wt % of R-143a and 4 wt % of R-134a. An alternative embodiment uses adouble-mixed refrigerant composed of 50 wt % of R-125 and 50 wt % ofR-143a. Refrigerator oil used for the refrigerating cycle must have goodcompatibility with the refrigerant. While ester oil and/or ether oil maybe used as the refrigerator oil, this embodiment uses ester oil as therefrigerator oil. It is found that preferably the ester oil is mainlycomposed of ester oil of fatty acid and has a dynamic viscosity of 2-70cSt at 40° C. and 1-9 cSt at 100° C. and at least two ester linkages ina molecule in order to cover a temperature range of −60° C. to +5° C.which is the usual specification range of a refrigerating apparatus.

[0035] This embodiment is devised as described below to realize arefrigerating apparatus which covers the temperature range of −60° C. to+5° C. in the refrigerating cycle using the above triple-mixedrefrigerant and the refrigerator oil similarly to a conventionalrefrigerating apparatus using a refrigerant containing chloride.

[0036] There is provided a protection switch 23 which is connected to ahigh pressure sensor 31 for detecting a pressure of a high pressurepiping 24 and to a low pressure sensor 32 for detecting a pressure of alow pressure piping 25, respectively so as to turn off the switch of theoperation circuit of a compressor motor when a limit value of a highpressure or low pressure is reached.

[0037] There is provided a pressure controller 15 which detects apressure of the condenser 2, decreases, when the detected pressurereaches a preset high pressure value, a capacity of the compressor bydecreasing the revolutions of the compressor motor and increases, whenthe detected pressure reaches a preset low pressure value, a capacity ofthe compressor by increasing the revolutions of the compressor motor.The revolutions of the compressor motor may be controlled stepwise usinga motor capable of changing the number of poles or controlledcontinuously in accordance with a pressure value by inverter control.Note, in this embodiment, when a pressure is reached to the preset highpressure value by the pressure controller 15, revolutions of each of theblower motors 81 and 82 is controlled to its full speed at the same timeto decrease the high pressure, whereas when a pressure is reached to thepreset low pressure value, the revolutions of each of the blower motors81 and 82 is decreased to increase the high pressure.

[0038] There is provided a liquid injection piping 12 for connecting theliquid refrigerant outlet piping 16 of the liquid receiver 3 disposeddownstream of the condenser to the scroll compressor 1. The liquidinjection piping 12 includes a strainer 11 and an electronic expansionvalve 10 and a liquid refrigerant is supplied into the intermediatepressure chamber of the scroll compressor 1 therethrough. A controller30 calculates amounts of control of the electronic expansion valve 10and the blower motors 81 and 82 by a previously input program inresponse to values detected by a thermistor 26 for detecting a liquidtemperature of the condenser 2, a thermistor 27 for detecting atemperature of intake air, i.e., a temperature of outside air suppliedto the condenser 2 and a thermistor 28 for detecting a discharge sidetemperature of the compressor 1. A control signal output unit 29 outputscontrol signals to the blower motors 81 and 82 for the condenser and theelectronic expansion valve 10 in response to a command from thecontroller 30.

[0039] The condenser 2 uses a heat exchanger whose piping has a diametersmaller than that of heat exchangers constituting the evaporators 61 and62. An this embodiment, the condenser 2 is composed of a heat exchangerwhose piping has a small diameter of about 7 mm so as to cover the abovetemperature range of the refrigerating apparatus.

[0040] A bypass piping 22 connected to a discharge gas piping 13 is alsoconnected to the outlet piping of the evaporators 61 and 62, i.e., to arefrigerant gas piping 17 through an electromagnetic valve 20 and acheck valve 21. This is for the purpose of causing a high pressure gasto escape to a low pressure side before the compressor 1 starts and thuscausing the electromagnetic valve 20 to “open” for a predeterminedperiod of time. With this arrangement, the compressor 1 can be smoothlystarted by balancing cyclic pressures on a high pressure side and a lowpressure side.

[0041] Next, the operation of this embodiment will be described withreference to FIG. 1.

[0042] A refrigerant gas compressed by the compressor 1 is condensed bythe condenser 2 through the discharge pipe 13 and a check valve 14,supplied to the expansion valves 51 and 52 and the evaporators 61 and 62through the liquid receiver 3, a liquid refrigerant piping 16 and thedrier 4 and evaporated therein to a gas. The gas is returned to theintake side of the compressor 1 from an intake piping 19 through therefrigerant gas piping 17, the strainer 18 and the accumulator 7.

[0043] Next, the liquid injection piping 12 will be described. A degreeof opening of the electromagnetic valve 10 is controlled depending upona discharge side temperature of the compressor 1. The thermistor 28detects the discharge temperature and compares it with a previouslyinput and set discharge temperature. When the detected dischargetemperature is higher than the set value, a degree of opening of thevalve 10 is increased, whereas when the detected temperature is lowerthan the set value, a degree of opening of the valve 10 is decreased.That is, a degree of opening of the expansion valve 10 is continuouslyadjusted by the controller 30 and the control signal output unit 29. Asdescribed above, the overheat of the compressor 1 can be prevented bycontrolling a discharge temperature of the compressor 1 and thus arefrigerating cycle operation can be stably carried out.

[0044] Since an amount of a refrigerant dissolved in refrigerator oil isincreased when an outside air temperature is low, a viscosity of therefrigerator oil is lowered. Therefore, an effect of the refrigeratoroil as a lubricant to the bearing portion of the compressor is reducedand the bearing portion is worn. In this embodiment, when an outside airtemperature is lower than a set temperature, a viscosity of therefrigerator oil is secured in such a manner that a degree of opening ofthe electronic expansion valve 10 in the liquid injection piping 12 isdecreased in response to a temperature detected by the thermistor 27 sothat an amount of a refrigerant supplied to the compressor 1 isdecreased and a discharge side temperature of the compressor 1 isincreased when it starts to reduce an amount of the refrigerantdissolved in the refrigerator oil in order to increase a viscosity ofthe refrigerator oil even in a slight amount. With this arrangement, thereliability of the bearing portion of the compressor can be improved.

[0045] Since a pressure at a high pressure side is increased when anoutside air temperature is high, the high pressure is controlled. Thatis, when it is found from a temperature detected by the thermistor 26that a temperature of a liquid refrigerant is high at the outlet of thecondenser 2, the high pressure is decreased by increasing an amount ofair to be supplied by increasing revolutions of the blower motors 81 and82 for the condenser. Further, when a temperature of the liquidrefrigerant is low at the outlet of the condenser 2, the high pressureis increased by decreasing the revolutions of the blower motors 81 and82 for the condenser.

[0046] Further, when it is found from a temperature detected by thethermistor 27 that an outside air temperature is high, a high pressureis decreased by increasing an amount of air to be supplied by increasingthe revolutions of the blower motors 81 and 82 for the condenser,whereas when the outside air temperature is low, the high pressure isincreased by decreasing an amount of air to be supplied.

[0047] These controls are effected by controlling the revolutions of theblower motors 81 and 82 by the controller 30 and the control signaloutput unit 29.

[0048] When a pressure in the condenser 2 is higher than a set value, acapacity control is effected by decreasing a capacity of the scrollcompressor 1 by the operation of the pressure controller 15 andrevolutions of each of the blower motors 81 and 82 is set to at its fullspeed to decrease a high pressure. When a pressure in the condenser 2 islower than the set value, a capacity of the scroll compressor 1 isincreased by the operation of the pressure controller 15 and revolutionsof each of the blower motors 81 and 82 is also decreased to increase ahigh pressure.

[0049] Note, the liquid receiver 3 includes a fusible plug 33 which hasa function for discharging a refrigerant when it is excessively heated.

[0050] The dryer 4 has an object for removing water mixed in arefrigerating cycle. A desiccating agent, which is used to the dryer 4in a refrigerating cycle employing the hydrocarbon fluoride refrigerantwhich does not contain chlorine as an operation refrigerant, is composedof synthesized zeolite in which each of fine holes extending to moleculeadsorbing cavities in a crystal structure has a diameter equal to orless than 3.3 angstroms which is smaller than a molecule of thehydrocarbon fluoride refrigerant which does not contain chlorine andlarger than a molecule of water. The dryer 4 may be positioned at theoil sump in the compressor 1, the oil sump of an oil separator or in theaccumulator 7. In this case, the number of parts can be reduced ascompared with a case that it is connected to a refrigerating cyclepiping, thus a manufacturing cost can be reduced and the leakage of agas caused by the improper mounting of it can be prevented.

[0051] Although the thermistors 26-28 are used in the aboverefrigerating cycle as means for detecting temperatures, an ON/OFFcontrol by thermostats may be employed in place of the thermistors.

[0052] Although a control can be continuously effected when thethermistors are used, the control is effected in an ON/OFF fashion whenthe thermostats are employed. Further, the above control may be effectedby the controller 30 and the control signal output unit 29 by detectingpressures in place of temperatures.

[0053] Next, other examples of the liquid injecting portion in theembodiment shown in FIG. 1 will be described with reference to FIG.2-FIG. 5.

[0054] In an example of FIG. 2, a liquid injection control is effectedby electromagnetic valves 341 and 342 and capillaries 351 and 352. Theelectromagnetic valve 341 is opened simultaneously with the start of thecompressor 1 so as to prevent the increase of a discharge sidetemperature of the compressor 1. When the discharge side temperature isfurther increased, the increased temperature is detected by thethermistor 28, and when it is higher than a set temperature, theelectromagnetic valve 342 is opened and an amount of an injected liquidis increased so that the overheat of the compressor 1 can be prevented.

[0055] An example of FIG. 3 will be described. The example of FIG. 3 isdifferent from that of FIG. 2 in that the liquid injection piping 12 isconnected to the lower oil sump of the liquid receiver 3. With thisarrangement, a liquid refrigerant can be stably used for a liquidinjection control at all times.

[0056] An example of FIG. 4 will be described. The example of FIG. 4 isdifferent from that of FIG. 1 in that only a liquid injection control iseffected. The liquid injection control in the example of FIG. 4 iseffected separately using the line of an injection valve 36 and the lineof the electromagnetic valve 341 and the capillary 351. Theelectromagnetic valve 341 is opened simultaneously with the start of thecompressor 1 so as to prevent the increase of a discharge sidetemperature of the compressor 1. Further, when it is found by atemperature or pressure sensor 37 connected to the discharge piping 13that a temperature or a pressure is higher than a set temperature orpressure, the injection valve 36 is opened, whereas when it is lowerthan the set temperature or pressure, the injection valve 36 is closed.With this arrangement, the overheat preventing operation of thecompressor 1 can be effected so that the refrigerating cycle operationcan be stably effected.

[0057] Next, an example of FIG. 5 will be described. The example of FIG.5 is different from that of FIG. 4 in that the liquid injection piping12 is connected to the lower oil sump of the liquid receiver 3. Withthis arrangement, a liquid refrigerant can be used for a liquidinjection control at all times without causing the shortage of it.

[0058] As described above, according to the present invention, since theliquid injection type scroll compressor is used together with the newrefrigerator oil having good compatibility with the new refrigerant, thenew refrigerant which does not contain chlorine having a possibility fordestroying the ozone layer can be used. Thus, there can be obtained anadvantage that a stable refrigerating cycle operation can be realized ina wide operating pressure and temperature equivalent to those of aconventional refrigerating apparatus.

[0059] Further, since water in the cycle piping can be effectivelyremoved by the dryer complying with the new refrigerant, the reliabilityof the compressor and other cycle components can be improved and atrouble of the refrigerating apparatus caused by water can be prevented.

What is claimed is:
 1. A refrigerator comprising a compressor, a condenser, a single or mixed HFC refrigerant, and a refrigerator oil composed of ester oil or ether oil, the refrigerator further comprising: an injection piping connecting from downstream of said condenser to said compressor, expansion equipment provided in said injection piping, an electromagnetic valve provided upstream of said expansion equipment in said injection piping, and a strainer provided upstream of said electromagnetic valve.
 2. A refrigerator comprising a compressor, a condenser, a single or mixed HFC refrigerant, and a refrigerator oil composed of ester oil or ether oil, the refrigerator further comprising: piping connecting from downstream of said condenser to said compressor, said piping including an electromagnetic valve and expansion equipment, and a strainer provided upstream of said electromagnetic valve.
 3. A refrigerator comprising a scroll compressor, a condenser, a single or mixed HFC refrigerant, and a refrigerator oil composed of ester oil or ether oil, the refrigerator further comprising: an injection piping connecting from downstream of said condenser to said scroll compressor, an expansion device provided in said injection piping, an electromagnetic valve provided upstream of said expansion device in said injection piping, and a dryer provided downstream of said condenser.
 4. A refrigerator comprising a compressor, a condenser, a single or mixed HFC refrigerant, and a refrigerator oil composed of ester oil or ether oil, the refrigerator further comprising: an injection piping connecting from downstream of said condenser to said compressor, an expansion device provided in said injection piping, an electromagnetic valve provided upstream of said expansion device in said injection piping, wherein said electromagnetic valve is controlled to open when said compressor is started.
 5. A refrigerator comprising a compressor, a condenser, a single or mixed HFC refrigerant, and a refrigerator oil composed of ester oil or ether oil, the refrigerator further comprising: an injection piping connecting from downstream of said condenser to said compressor, an expansion device provided in said injection piping, an electromagnetic valve provided upstream of said expansion device in said injection piping, wherein said electromagnetic valve is controlled to close when said compressor is stopped.
 6. A refrigerator according to claim 4, wherein said electromagnetic valve is controlled to close when said compressor is stopped.
 7. A refrigerating apparatus for constituting a refrigerating cycle including at least a scroll compressor and a condenser, further comprising: piping connecting from downstream of said condenser to said scroll compressor, a dryer disposed in said refrigerating cycle on a downstream side of said condenser to remove water mixed into said refrigerating cycle. wherein a single or mixed HFC refrigerant, is used as a refrigerant for said refrigerating apparatus ester oil or ether oil is used as refrigerator oil for said refrigerating apparatus, and said piping includes an electromagnetic valve and an expansion device provided downstream of said electromagnetic valve.
 8. A refrigerating apparatus for constituting a refrigerating cycle including at least a compressor and a condenser, further comprising: piping connecting from downstream of said condenser to said compressor, wherein a single or mixed HFC refrigerant is used as a refrigerant for said refrigerating apparatus, ester oil or ether oil is used as refrigerator oil for said refrigerating apparatus, and said piping includes an electromagnetic valve and an expansion device provided downstream of said electromagnetic valve, and further comprising: a strainer provided upstream of said electromagnetic valve.
 9. A refrigerator comprising a scroll compressor, a condenser, a single or mixed HFC refrigerant, and a refrigerator oil composed of ester oil or ether oil, the refrigerator further comprising: an injection piping connecting from downstream of said condenser to said scroll compressor, an expansion device provided in said injection piping, an electromagnetic valve provided upstream of said expansion equipment in said injection piping, and a dryer disposed in said refrigerating cycle on a downstream side of said condenser to remove water mixed into said refrigerating cycle. 